Windable insulating tape with spacers and method of manufacturing such tape

ABSTRACT

AN INSULATING TAPE WITH SPACERS FOR FORMING AXIAL CHANNELS IN WINDINGS OF COILS FOR TRANSFORMERS IS FORMED BY APPLYING AT SPACED INTERVALS ALONG A SIDE OF A CONTINUOUS BASE INSULATING TAPE COATED WITH AN ADHESIVE ROLLS OF AN INSULATING TAPE LIKEWISE COATED ON ONE SIDE WITH AN ADHESIVE AND APPLYING HEAT AND PRESSURE. EACH ROLL HAS A PROJECTING PORTION ALSO ADHESIVELY SECURED TO THE MAIN TAPE.

April 20, 1971 L. ANDERSON ETAL 3,575,775

WINDABLE INSULATING TAPE WITH SPACERS AND METHOD OF MANUFACTURING SUCH TAPE Filed Aug. 4, 1969 INVE T Lana ANDERSSON s'ne LARBO N 0R STURE LINDSKOG BY OTTO JOHAN55DN United States Patent Office 3,575,775 Patented Apr. 20, 1971 3,575,775 WINDABLE INSULATING TAPE WITH SPACERS AND METHOD OF MANUFACTURING SUCH TAPE Lars Andersson, Stig Larbo, Sture Lindskog, and Otto Johansson, Ludvika, Sweden, assignors to Allmiinna Svenska Elektriska Aktiebolaget, Vasteras, Sweden Filed Aug. 4, 1969, Ser. No. 847,014 Claims priority, application Sweden, Aug. 30, 1968, 11,646/68 Int. Cl. H01f 27/32; B32b 1/04 US. Cl. 161-39 4 Claims ABSTRACT OF THE DISCLOSURE An insulating tape with spacers for forming axial channels in windings of coils for transformers is formed by applying at spaced intervals along a side of a continuous base insulating tape coated with an adhesive rolls of an insulating tape likewise coated on one side with an adhesive and applying heat and pressure. Each roll has a projecting portion also adhesively secured to the main tape.

BACKGROUND OF THE INVENTION (1) Field of the invention In order to effect axial cooling channels in windings for coils for transformers and similar electrical apparatus, insulating tape is sometimes used with spacers glued on. This tape is applied helically, preferably during the winding. The spaces thus occurring between the layers of the winding form axial cooling channels inside the winding.

(2) The prior art Such a tape with spacers can be manufactured in many ways. According to one known method, rectangular blocks of fiber material are glued on a paper tape. However, it has been found that the blocks may become detached from the tape and fall down between the turns of the winding, with the risk that the cooling channels become at least partially blocked. Another proposal is to use a single tape and have this act both as carrier and as the material for the spacers. At certain points part of the tape is rolled up to form a double spiral which is pressed and glued together to form a spacer. Such a tape, however, has the disadvantage that, if the adhesion is not entirely satisfactory, the spiral opens up when the tape is applied under a certain tension in the winding. The spacer thus disappears and only the thin paper tape is wound on.

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a windable tape with spacers arranged at a certain distance from each other in order to form axial cooling channels in windings for transformers and similar electrical apparatus in which a tape of insulating material pretreated with adhesive is provided with said spacers. The method is characterised in that the spacers are produced from a second tape of insulating material pretreated with adhesive by rolling up a certain length of the second tape to a spiral which is applied on the base tape and attached to it by means of heating and pressure.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing shows a strip of tape manufactured by the method according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Two strips are used when manufacturing the tape, suitably consisting of the same material and having the same width. The tapes consist of insulating material, suitably paper and are pretreated on one side with an adhesive which is solid at room temperature and only adheres after heating. One tape 1, the base tape, is provided with adhesive on the upper side and forms the carrier in the finished product. A spacer 2 is formed by rolling up a certain length of the second tape 3 into a spiral with the adhesive side of the tape facing inward and this spiral is placed on the base tape. The base tape 1 and the spiral are heated, for example by blowing hot air over them, and the spiral is simultaneously pressed against the base tape. In order to increase the contact surface between the base tape and the spacer, a piece 4 of the second tape 3 is left outside the spiral and this piece, which has its adhesive surface facing the adhesive surface of the base tape, is pressed against the base tape and heated. The part of the second tape 3 which is thus adhered to the base tape is approximately the same length as the finished spacer, thus doubling the total contact surface between the two tapes.

The method according to the invention provides a tape with the best possible properties. Since the carrier tape is unbroken, the] disadvantage is completely eliminated which exists with the known tapes that the rolled double spiral becomes unrolled if the tape is stretched and the adhesive surfaces open. The large contact surface between the spacer and the base tape ensures that the spacer is securely attached to the base tape.

We claim:

1. Method of manufacturing a windable tape with spacers arranged at a distance from each other in order to form axial cooling channels in windings for transformers and similar electrical apparatus, which comprises applying on a continuous base tape of insulating material pretreated with adhesive spacers produced from a second tape of insulating material pretreated with adhesive by rolling up a length of the second tape into a spiral and attaching the rolled up length to the base tape by heat and pressure. I

2. Method according to claim 1, in which comprises leaving a piece of the length of the second tape which is rolled into a spiral free outside the spiral and adhering this piece to the base tape.

3. A windable continuous base tape with spacers arranged thereon at distances from each other, the base tape comprising insulating material coated with an adhesive, and the spacers comprising rolled lengths of tape of insulating material coated with an adhesive on one side and adhesively secured to the base tape.

4. A windable tape according to c aim 3, in which each spacer has a free piece outside the spiral adhesively secured to the base tape.

References Cited UNITED STATES PATENTS 9/1962 Rabins 336-60 2/1966 Ford 336-60X 

